The invention relates to a component placement machine for placing components on a printed circuit board, comprising:                a transport device for transporting printed circuit boards in an X-direction,        on either side of the transport device, respectively, a first and a second feeder area, in each of which there is at least one feeder with components,        a Y-slide, which is drivable in the X-direction, and        a placement head on said Y-slide, which placement head is drivable in a Y-direction.        
Such a machine is known from WO-A-9738567. This machine can be very flexibly used for different types of printed circuit boards. The placement head can reach all positions of the feeder area and of the area above a printed circuit board. The transport of printed circuit boards is relatively simple. The printed circuit boards only have to be clamped at the edges (in the X-direction). By means of a camera, the exact position of the printed circuit board can be determined. A drawback of this machine is, however, that the output, i.e. the number of components which can be placed per unit of time, is limited.
Placement machines by means of which very many components (60,000-90,000 comp/h) can be placed on printed circuit boards are known. Such machines have a large number of fixed Y-slides, each slide having a placement head which can be moved in the Y-direction with a large stroke and in the X-direction with a small stroke. These machines have a so-called indexed transport system for the printed circuit boards, i.e. the printed circuit boards are always transported over a fixed distance in the X-direction. Such a transport system includes a slide on which there are a number of positioning pins which are inserted into holes of the printed circuit boards, whereafter said positioning pins advance the printed circuit boards simultaneously over a predetermined distance in the X-direction, after which the printed circuit boards are supported at the side edges, and subsequently the pins are withdrawn from the holes and the slide returns to its starting position. In one placement period, generally components can be placed only on a part of the printed circuit board. After the printed circuit boards have been advanced in an indexed manner, components can be placed on a next part of the printed circuit board in the subsequent placement period. The fixed Y-slide, the limited stroke of the placement head in the X-direction and the indexed transport system for the printed circuit boards contribute substantially to achieving a high output. A drawback of such machines resides in the limited flexibility, i.e. when other types of printed circuit boards have to be provided with components, a number of machine parts have to be moved or replaced, whereafter the new setting has to be re-calibrated. These changes relate particularly to the parts necessary for supporting and transporting the printed circuit boards. It takes approximately 2 to 4 hours to carry out such changes. During this period of time, the machine is idle. Another drawback resides in that such machines are sensitive to cluster formation. That is to say, if the components are not uniformly distributed over the printed circuit board, but instead are located so as to form concentrations (clusters), the output is adversely affected.